One dimensional (1D)γ-alumina nanorod linked networks: Synthesis, characterization and application

摘要

A series of one dimensional (1D) alumina nanocomposites were prepared by a soft template sol-gel synthesis. The materials were calcined at 773 K and an extensive characterization was carried out. Several arrays and individual 1D nanorods forming a linked network were observed by HRTEM. The presence of alumina nanorods induced novel electronic properties for alumina carrier. A decrease on the band gap energy detected by DRS UV-vis, and a shift on the binding energy of Al 2p core-level was observed by XPS revealing an increase on the conduction character. This unusual behavior for alumina materials is probably related with an oxygen deficiency over the nanorod surface confirmed by TEM-EDX analysis. Also, it was possible to correlate some surface morphological changes with the average molecular weight (AMW) of the "Pluronics". The results show that a decrease for the nanorod average length is observed with an increase on the pluronic AMW. Besides, a proportional increase for the nanorods average diameter with the pluronic AMW is also observed. These results imply that it is possible to control de morphological characteristics of the nanostructures. The formation of the nanorods linked network give a rise to materials with high specific surface area and a very narrow pore size distribution in the mesoporous range. Some materials were used as a support to prepare NiWS catalysts and were tested in the HDS of dibenzothiophene with promising results. Finally a possible mechanism for the formation of the alumina nanorods is proposed in this work.